Rate transient analysis methods for water-producing gas wells in tight reservoirs with mobile water

Tight gas reservoirs with mobile water exhibit multi-phase flow and high stress sensitivity. Accurately analyzing the reservoir and well parameters using conventional single-phase rate transient analysis methods proves challenging. This study introduces novel rate transient analysis methods incorporating evaluation processes based on the conventional flowing material balance method and the Blasingame type-curve method to examine fractured gas wells producing water. By positing a gas-water two-phase equivalent homogenous phase that considers characteristics of mobile water, gas, and high stress sensitivity, the conventional single-phase rate transient analysis methods can be applied by integrating the phase's characteristics and defining the phase's normalized parameters and material balance pseudo-time. The rate transient analysis methods based on the equivalent homogenous phase can be used to quantitatively assess the parameters of wells and gas reservoirs, such as original gas-in-place, fracture half-length, reservoir permeability, and well drainage radius. This facilitates the analysis of production dynamics of fractured wells and well-controlled areas, subsequently aiding in locating residual gas and guiding the configuration of well patterns. The specific evaluation processes are detailed. Additionally, a numerical simulation mechanism model was constructed to verify the reliability of the developed methods. The methods introduced have been successfully implemented in field water-producing gas wells within tight gas reservoirs containing mobile water.